1. Field of the Invention
This invention relates to packaging, in particular to a packaging container and to a sheet material blank from which the container can be made.
2. Description of the Prior Art
Various packaging cartons and blanks from which the cartons can be made are known from, for example, EP-A-0132824; EP-A-0465834; EP-A-0547987; FR-A-1437100; FR-A-2535685; GB-A-466947; GB-A-1118696; U.S. Pat. No. 2,097,647; U.S. Pat. No. 3,447,732; U.S. Pat. No. 3,9057,180; U.S. Pat. No. 3,998,380 and U.S. Pat. No. 4,588,122. Of these, U.S. Pat. No. 3,957,180 and U.S. Pat. No. 4,588,122 each disclose a sheet material blank comprising a row of five body panels, a row of five bottom and closure panels, a row of five top closure obturating panels and a row of five top closure sealing panels, all extending parallelly to each other and with score lines generally dividing the sheet material into the various panels. Two alternate inner panels of the row of the top closure obturating panels are divided into triangular sub-panels by oblique score lines. In the forming of the carton, the rows are folded about score lines perpendicular to the rows and the end panels of each row are sealed together to form a liquid tight seal extending along the carton sleeve so formed. The bottom end closure panels are then folded together and sealed to form a liquid tight bottom end closure and the carton is then filled. After filling, the top end closure panels are folded to cause each group of triangular sub-panels to project outwards and to fold upon itself that sealing panel adjacent the group so that the sealing panels extend as a fin in the form of generally two thicknesses of the sheet material, whereupon the sealing panels are sealed together to form a liquid tight sealing fin sealing the top end closure. The sealing fin is turned down to lie flat against parts of the obturating panels at one side of a central plane of the carton. In U.S. Pat. No. 3,957,180, the outwardly projecting groups of triangular sub-panels, with the adjacent end zones of the sealing fin and forming triangular flaps at respective ends of the fin, are turned downwards to lie flatly against the respective adjacent body panels and are tacked to those body panels. In U.S. Pat. No. 4,588,152, the two triangular flaps are instead turned upwards to lie flatly against the top wall of the carton and are tacked to that wall. EP-A-0465834 discloses a carton similar to that of U.S. Pat. No. 3,957,180, except that it has been made from a web constituting, in effect, a row of such blanks and progressively folded into a tube which is progressively filled and cross-sealed and severed to form sealing fins in both the top and bottom closures of each carton.
To open the carton of U.S. Pat. No. 3,957,180, one of the triangular flaps is detached from its adjacent body panel and lifted to a horizontal condition. Then its sealing panel, which is in a condition sealed to itself, is torn or cut away from the adjacent sealing panels and thereupon pulled away from those adjacent panels to tear off the adjacent tips of the adjacent group of triangular sub-panels to form a pouring opening. The sheet material at the two nearby corners of the carton is provided with diamond-shaped arrays of score lines whereby, when the consumer grasps the carton across those corners between the thumb and fingers, the opening is brought to a shape more appropriate for pouring.
In EP-A-0465834, opening is achieved by again detaching one of the triangular flaps from its adjacent body panel, fitting in and tearing off a section of the sealing fin along lines of perforation extending from the middle of the fin to the apex of the triangular flap to reveal a pouring opening. In order to obtain a desired raising of the rear end of the pouring opening, the obturating panels of the top end wall of the carton are provided with two score lines which diverge from the rear end of the opening. The rear part of that wall is provided with two other score lines which, together with the two score lines diverging from the rear end of the opening, enclose a central, generally, rhomboid area of the wall. Thereby the wall is intended to acquire a tendency to fold at those score lines in conjunction with the folding up and widthwise squeezing of the triangular flap when the carton is to be opened. This is intended to make it possible for the rear end of the pouring opening to be raised a sufficient extent in relation to the surface of the packaged liquid that air can flow into the carton even when the consumer has not opened it completely or when the liquid, owing to its viscosity, has an increased tendency to surge.